The present disclosure relates generally to cardiac surgical bypass systems and, more particularly, to a cardiac imaging system and method for planning minimally invasive direct coronary artery bypass surgery (MIDCAB).
According to American Heart Association statistics, over 500,000 coronary artery bypass grafts (CABGs) are performed every year in the United States alone. In coronary artery disease, the arteries that bring blood to the heart muscle (i.e., the coronary arteries) become clogged by plaque, which is a buildup of fat. During CABG surgery, the blood is rerouted around the clogged arteries in order to improve blood flow and oxygen to the heart. A healthy blood vessel, such as the left internal mammary, is detached from the chest wall and is thereafter used to circumvent the blocked area. Alternatively, a segment of vein from the leg can also be used for the CABG. One end of the vessel/vein is sewn onto the aorta (the large artery leaving the heart), while the other end is attached or “grafted” to the coronary artery beyond (or past or distal to) the blocked area. Patients may undergo multiple by-passes at the same time.
Cardiopulmonary bypass using a heart-lung machine is typically used to stop the movement of the heart at the time of the CABG procedure. Although CABG is the treatment of choice in many cases (and is one of the most common surgical procedures performed today), there are several potential complications from this surgery, as well as from the cardiopulmonary bypass technique required during the CABG procedure. In a recent study published in the New England Journal of Medicine, 53 percent of patients had diminished mental acuity at the time of discharge from the hospital after a CABG procedure. In addition to the prolonged hospital stay and the possible need for transfusions, sternal wound infection at the site of the incision can occur in 1 to 4 percent of patients and carries a mortality (death) rate of about 25 percent. Furthermore, as many as 8 percent of patients may develop kidney dysfunction as a result of the CABG procedure.
As a result of the above described problems associated with CABG, minimally invasive direct coronary artery bypass (MIDCAB) surgery has been used as an alternative in some patients, wherein the MIDCAB procedure does not require reliance on the heart-lung machine. In MIDCAB surgery, a 10-12 cm access incision is made in the patient's chest, after which several different instruments are used to stabilize the heart at the time of surgery. The surgeon then connects a graft to the diseased coronary arteries while the heart is beating without artificial support. Due to the nature of the operation, grafting (the attaching of the vessels) must be done under the surgeon's direct vision and the coronary artery that is to be bypassed must lie directly beneath the incision (surgical opening). Consequently, this procedure is currently used in only a limited number of patients, and only if it is known that just one or two of the arteries require a bypass.
Although it is estimated that over 30 percent of patients who need CABG may be suitable candidates for MIDCAB surgery, presently the procedure is performed in only 10 percent of patients because of this unknown factor. There is, therefore, a distinct need for an improved system and method to make this procedure more effective and easier to perform.